At a hybrid vehicle which is configured to run in a motor running mode where the vehicle runs only on a motor and in a hybrid running mode where the vehicle runs on both an engine and the motor while switching the motor running mode and the hybrid running mode to each other, a technique is known in which, in a case where the mode transits from the motor running mode to the hybrid running mode, a clutch provided between the motor and the engine is engaged and thus the engine is started up by the motor that is used to run the vehicle. Thus, according to the known technique, the engine is started up without additionally providing, for example, a starter motor. Related to such a known technique, a technique is also known where, in a case where a drive power requested by a driver increases and the engine is brought to be started, rotation speed of the engine is increased quickly by releasing a clutch which is provided between the motor and a vehicle drive shaft for connecting and disconnecting the motor and the vehicle drive shaft relative to each other as described in, for example, JP2012-131497A (hereinafter referred to as Patent reference 1).
According to the known technique described in Patent reference 1, however, the clutch is released and thus the vehicle drive shaft is disconnected from the motor at a time point when the requested drive power increases and the engine is brought to be started. Accordingly, the drive power is not transmitted from when the driver presses on an accelerator until when the clutch is engaged again. Consequently, according to the known technique, it is difficult to make an appropriate and accurate response to the driver's request for running the vehicle.
In addition, according to the known technique, at a start-up of the engine, the clutch is allowed to slide and thus the drive power is restricted from changing, which may heat up the clutch and may cause a failure. Consequently, according to the known technique, a high cooling performance needs to be provided in order to prevent the clutch from being heated.
A need thus exists for a vehicle control apparatus which is not susceptible to the drawback mentioned above.